Spec drift playground

The manifest on the left is the source of truth. The gate on the right is not a model: it re-derives what the contracts and tests must contain and compares. Nothing here is simulated by an LLM — it's the same kind of check that runs in CI, with the numbers made small enough to read.

Try adding an invariant without a test, or relaxing idempotency on a POST. The build result changes before anything reaches a reviewer.